Automatic paralleling device for alternating-current generators.



No. 806,318. PATENTED DEC. 5, 1905. G. A. BURNHAM. AUTOMATIC PARALLELING DEVICE FOR ALTERNATING CURRENT GENERATORS.

APIFLIOAI'ION FILED JAN. 14, 1904.

UNITED, STATES PATENT OFFICE.

G'EORGE'A. BURNHAM, OF WILLIMANTIC, CONNECTICUT.

AUTOMATIC PARALLELING DEVICE FOR ALTliRNATlNG-CURRENT GENERATORS.

W illimantic, in the county of Windham and State of Connecticut, have invented certain new and useful Improvements in Automatic Paralleling Devices for Alternating-Current Generators, of which the following is a full, clear, and exact description.

This invention is an automatic paralleling device for alternating-current generators, and is designed to automatically throw two or more generators into parallel connection on a main circuit at the moment their phases are in synchronism.

The invention consists, essentially, of an electromagnet and means for connecting it in series with the phases of the various generators to be paralleled, said magnet being wound to actuate a paralleling-switch only when the magnetic flux is brought to the maximum by the synchronism of the phases.

The mechanism required to carry out my invention is very little and can be readily attached to switchboards already installed.

In the accompanying drawings, Figure 1 is a conventional plan of the circuits and apparatus of an alternating-current switchboard for two generators, the bus-bars being indicated as circuit-lines. Fig. 2 is a side elevation of an electromagnetic switch, and Fig. 3 is a plan of the same.

The main bus-bars of the switchboard are indicated by A and A and the synchronizing bus-bars by B and B. No. 1 and No. 2 indicate the two generators and S and S the main switches for connecting them, respectively, with the main bus-bars. For connecting each generator with the synchronizing bus-bars branch circuits 1 1 and 2 2 are connected across the brushes of the respective generators and each includes the primary winding of a transformer T or T, the terminals of the sec- Specification of Letters Patent. Application filed Ma 14, 1904.. Serial No. 188,987.

Patented Dec. 5, 1905.

the voltage of the respective generators. The synchronizing-bars also contain plugging-in points 19 and p to connect the secondary currents of the generators to be paralleled in series.

E is an electromagnet in the form of a solenoid having a core 0, carrying at its outer end a roller 0, which normally supports a switch-leverfin its open position. This lever tends to close under the action of spring f and thus connect together the points 3 1 and 5 6. The magnet is constructed to release the switch only at the instant when the strongest flux, created when the various currents flowing through it are in step, occurs. This magnet is mounted on the switchboard and connected in series with the two synchronizing-bars B and B; but it is normally short-circuited by a push-switch 2'. The points 3 and 5 of the switch are the terminals of two wires 7 and 8, connected across the brushes of No. 1 generator, while the terminals 4 and 6 are the terminals of two wires 9 and 10, connected across the brushes of No. 2 generator, or which might be any other generator in the station, if there were more than two, and which it is desired to parallel with No. 1.

The operation of paralleling is as follows: Let it be assumed the generator No. 1 is connected to line, as shown by the dotted lines in switch S, and that generator No. 2 is to be paralleled with it. Branch 1, 1 of generator No. 1 and branch 2, 2 of generator No.2, are closed. Points 1) and p are left open until the voltage of No. 2 generator has been brought up to normal. Then plugs are inserted in p and 39, thus connecting the phaselamp and the electromagnet in series with both currents, the current being shunted, however, around the magnet by the pushswitch When the phase-lamp indicates that the phases of the two machines are nearly in step, the operator will push the switch 2' and. hold the shunt open, thus directing the currents through the magnet E. At the moment the phases are in step, the magnetic flux then being strongest, the magnet releases the switch-lever f and the points 3 and tand 5 and 6 are bridged, thus paralleling the two machines, as can be seen by the circuits heretofore described. The main switch S of generator No. 2 can now be closed at pleasure. It is obvious that any number of generators can be cut into the main circuit in succession in the same manner, it being necessary only to throw their secondary currents into series IIO mally closed shunt around said electromag- I netic switch and paralleling circuits controlled by said switch.

with those of the active generators and allow them to energize the magnet E, corresponding to the generator to be cut in.

Having described my invention, I claim- In witness whereof I subscribe my signature 5 A means for paralleling alternating-current in presence of two witnesses.

generators, comprising transformers supplied G. A. BURNHAM.

by the generators to be connected, a circuit Witnesses: including the secondary winding of said trans- W. E. FIsK,

formers and an electromagnetic switch, a nor- 7 F. L. ALPAUGI-I. 

